Targeting apparatus for use in a medical procedure

ABSTRACT

A universal targeting apparatus includes a generally U-shaped body having one end configured to be coupled to the proximal end of the intramedullary implant and a mounting portion at an opposite end of said body. An arm is rotatably mounted to the mounting portion of the U-shaped body and includes bores defined at its opposite ends. Each bore is arranged at a different angle to correspond to the angle of a transverse aperture in the intramedullary implant. The arm can be rotated so an appropriate one of the angled bores is aligned with the transverse aperture to serve as a guide for creating targeting holes in the bone.

BACKGROUND

The present disclosure relates generally to instrumentation used in amedical procedure, and more particularly, relates to a guide ortargeting apparatus used in the reduction of a hip fracture.

A procedure regularly performed by orthopaedic surgeons is the reductionof a hip fracture caused by trauma. The site of this type of fracturetypically exists at the proximal portion of the femur below the femoralhead. In order to reduce a fracture of this type, an elongated lag screwis threadingly advanced into the shaft, neck, and head of the femur. Incertain procedures, the proximal end of the lag screw is secured to abone plate. Cortical screws are used to secure the bone plate to thefemur distal to the fracture site. Tightening of the lag screwcompresses the bone fragments together and facilitates healing of thefemur. Many devices have been designed for this type of reductionincluding the devices disclosed in U.S. Pat. Nos. 4,438,762, 3,554,193,and 2,526,959, the disclosures of which are incorporated herein byreference in their entirety.

In other procedures, a stabilizing element, such as an intramedullaryrod or nail, may be advanced into the medullary canal of the femoralshaft. The intramedullary rod includes a transverse aperture that isoriented at an appropriate angle to support and anchor the proximalportion of the lag screw. In some cases, a compression screw is alsointroduced into the fractured bone to reduce the fracture. Thecompression screw also extends through the intramedullary rod adjacentthe lag screw. An example of a device of this type is disclosed in U.S.Pat. No. 5,562,666 to Brumfield, the disclosure of which is incorporatedherein by reference.

In many surgical procedures, various jigs or similar apparatuses areused to guide the creation of targeting holes in the bone. Morespecifically, jigs or targeting devices may be used to guide drillingfor and insertion of fracture fixation screws, such as the lag andcompression screws described above. Proper targeting is more problematicfor fixation systems utilizing intramedullary rods/nails, rather thanexternal plates because the transverse openings in the intramedullaryimplant are contained within the bone and are not directly visible.While various imaging devices may be used to guide a drilling operationor screw insertion, the images are planar and do not easily providethree-dimensional targeting or alignment. Thus, various jigs ortargeting devices have been developed to facilitate various steps in thefracture reduction and fixation process.

It is a goal of designers of medical instrumentation to design apparatusused in hip fracture reduction procedures that facilitate implantationof the fracture fixation components in as minimally invasive manner aspossible. While many targeting jigs meet this goal, these priorapparatuses are often complex and require assembly of multiplecomponents. Non-modular devices are known that eliminate the pluralityof components found in prior modular systems, but at the cost ofnon-universality—i.e., non-modular devices are designed for only certainspecific fixation arrangements, such as a specific angular orientationof a lag screw relative to an intramedullary rod/nail.

What is needed therefore is an assembly used in hip fracture reductionprocedures that facilitates implantation a fracture fixation apparatusand simplifies the procedure. The system should be modular and universalwithout the need for the surgeon to assemble several components beforethe alignment and targeting steps can be commenced. There is also a needfor such an assembly that minimizes or eliminate potential alignmenterrors that may occur during the procedure.

SUMMARY

To address these needs, a universal targeting apparatus is provided fortargeting a transverse aperture in an intramedullary implant, such as arod or bone nail, for introducing a lag screw into the aperture, inwhich the transverse aperture has an aperture axis that is oriented atone of at least two angles relative to the longitudinal axis of theintramedullary implant. In one embodiment, the targeting apparatuscomprises a generally U-shaped body having one end configured to becoupled to the proximal end of the intramedullary implant and a mountingportion at an opposite end of the body. The mounting portion define aplane with the intramedullary implant when the body is coupled thereto,the plane containing the aperture axis. The apparatus further comprisesan arm rotatably mounted to the mounting portion of the U-shaped bodythat has a first portion and a second portion offset from the firstportion. The first portion defines at least one first targeting borewith a longitudinal first axis, while the second portion defines atleast one second targeting bore with a longitudinal second axis. In oneaspect, the arm is configured so that the first axis is aligned with anaperture axis oriented at one of the at least two angles when the arm isrotated relative to the mounting portion to a first position in whichthe first axis resides within the plane, and so that the second axis isaligned with an aperture axis oriented at a different one of the atleast two angles when the arm is rotated to a different second positionin which the second axis resides within the plane.

In certain embodiments, the arm is an elongated bar and the first andsecond portions are at opposite ends thereof. In one specificembodiment, the arm is mounted to the mounting portion to rotate aboutan axis in the plane. In another specific embodiment, the arm is mountedto the mounting portion to rotate about an axis perpendicular to theplane. In either embodiment, the targeting arm is configured so thataxis of each of the targeting bores will align with the aperture axis ofthe intramedullary implant when the apparatus is connected to theimplant. The apparatus may incorporate a locking mechanism to lock thetargeting arm in one of the operative targeting positions so that thecorresponding targeting bore may used to create a path in the bone orintroduce a lag screw into the implant and bone fracture.

In certain embodiment, the locking mechanism may include a lockingmagnet mounted to the mounting portion and complementary magnets mountedin each of the first and second portions of the targeting arm. Thecomplementary magnets are configured to be magnetically attracted to thelocking magnet to magnetically hold the targeting arm in an operativeposition. In another embodiment, the locking mechanism includes adepressible pin mounted in one of the arm and the body, and a recessdefined in the other of the arm and the body, the recess configured toreceive the depressible pin in locking engagement.

In one alternative embodiment, the mounting portion includes two armsspaced apart to define a slot, and the arm is mounted to the mountingportion for rotation within the slot. In this embodiment, the arm isarranged to rotate within the plane defined by the longitudinal axis ofthe intramedullary implant and the axis of the transverse aperture inthe implant.

One benefit of the targeting apparatus disclosed herein is that it isuniversal in the sense that a single apparatus may accommodate differentlag screw angles of an intramedullary implant used for fracturereduction and fixation. Another benefit is that the disclosed apparatusdoes not require assembly by the surgeon at the surgical site, althoughthe apparatus can accommodate replaceable components to satisfy severallag screw axis angles.

DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded perspective view of one embodiment of a targetingapparatus disclosed herein, along with an intramedullary implant towhich the apparatus is mounted.

FIG. 2 is an exploded perspective view of the targeting apparatus shownin FIG. 1, with the apparatus viewed from a different angle.

FIG. 3 is a perspective view of the targeting apparatus shown in FIGS.1-2, with the apparatus assembled and mounted to the intramedullaryimplant in a first position.

FIG. 4 is a top view of a targeting arm of an alternative design for usein the apparatus shown in FIG. 1-3.

FIG. 5 is a perspective view of a modified targeting apparatus shownwith the apparatus in a rotated second position.

FIG. 6 is a perspective view of the targeting apparatus shown in FIG. 5with the apparatus in a different third position.

FIG. 7 is an exploded perspective view of a targeting apparatusaccording to a further embodiment disclosed herein.

FIG. 8 is an exploded perspective view of the targeting apparatus shownin FIG. 7, as viewed from a different angle.

FIGS. 9 a-c are perspective views of the targeting apparatus shown inFIGS. 7-8, with the apparatus depicted in sequential positions.

DESCRIPTION OF THE EMBODIMENTS

While the assembly described herein is susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and will herein bedescribed in detail. It should be understood, however, that there is nointent to limit the assembly to the particular forms disclosed, but onthe contrary, the intention is to cover all modifications, equivalents,and alternatives falling within the spirit and scope of the invention asdefined by the appended claims.

Referring to FIGS. 1-3, a targeting apparatus 30 is shown mounted to anintramedullary implant 10. It is understood that the intramedullaryimplant 10 would be implanted within the intramedullary canal of thefemoral shaft when used in the reduction and fixation of a hip fracture.In accordance with a typical hip fixation procedure, the stem 12 of theintramedullary implant is implanted with the proximal end 18 accessibleat the exposed surgical site. The stem 12 is oriented using knowntechniques so that the transverse apertures 14 and 15 are aligned withthe femoral head and the fracture. The transverse aperture 14 is sizedto receive a lag screw to reduce and fix the fracture in a known manner.In some procedures, a compression screw may be introduced through thesecond transverse aperture 15, again in a known manner.

The intramedullary implant 10 preferably defines a bore 19 extendingalong the longitudinal axis of the stem 12, at least part way along thelength of the stem. The bore 19 may define internal threads 22 at theproximal end 18 that are engaged by an insertion tool. The proximal endmay also define notches 20 that are also engaged by the insertion toolto facilitate introduction of the intramedullary implant 10 into thefemoral shaft.

As shown in FIGS. 1-2, the lag screw transverse aperture 14 is alignedso that the aperture axis A is aligned at a non-perpendicular angle Xrelative to the longitudinal axis L of the stem 12. This angularorientation corresponds to the non-perpendicular position of the femoralhead and neck relative to the femoral shaft. Depending upon the anatomyof the femur and the nature of the fracture, the lag screw may beintroduced into the femoral head at different angles. Thus, the angle Xof the transverse aperture 14 may be different between differentfixation procedures. In the majority of hip procedures, the angle X iseither 125° or 130° relative to the longitudinal axis L. In a fewernumber of cases other entry angles are indicated.

The targeting apparatus 30 provides a universal apparatus that iscapable of targeting drilling and screw insertion for the range of hipprocedures. The apparatus 30 includes a generally U-shaped body 32 witha targeting arm 34 pivotably mounted to the body. The body 32 includes aconnection end 36 that is configured to be mounted to the proximal end18 of the intramedullary implant 10. An intermediate portion 44 extendsfrom the connection end 36 to the mounting portion 46, to which thetargeting arm 34 is mounted, as described herein.

The configuration of the connection end 36 of the targeting apparatusbody is thus dictated by the configuration of the intramedullaryimplant. For the typical configuration of the intramedullary implantdescribed above, the connection end 36 includes a collar 37 sized toabut the proximal end 18. Prongs 39 extending from the collar are sizedto fit within the notches 20 in the end of the member 10. A fastener 41,such as a screw, extends through the collar 37 and into engagement withthe internal threads 22 in the bore of the intramedullary implant.

The interaction of the prongs and notches, and the fastener and internalthreads, effectively lock the body 32 of the targeting apparatus in apredetermined position relative to the stem 12 and transverse openings14, 15 of the member 10. More particularly, in this predeterminedposition the targeting apparatus 30 resides in the plane containing thelag screw transverse aperture 14 and the fractured bone segment to bereduced and fixed. Put another way, the mounting portion 46 includes amounting axis 48 that falls in the plane defined by the aperture axis Aand the longitudinal axis L of the intramedullary implant. Thus, theengagement of the connection end 36 to the proximal end 18 of the member10 provides the first step in the alignment and targeting function ofthe apparatus 30.

The intermediate portion 44 of the apparatus 30 forms the base of thegeneral U-shape of the body 32. The portion 44 laterally offsets themounting portion from the connection end so that the mounting portion 46is freely accessible outside the patient's limb. The length of theintermediate portion is sized to accommodate the girth of a typicallimb. However, the targeting arm must be supported sufficiently close tothe intramedullary implant to avoid targeting errors that may be causedby having to traverse the distance D (FIG. 1) between the targeting armand the transverse aperture 14. For instance, when the targeting arm isused to guide a drill to prepare a bore in the bone to receive a lagscrew, the greater the distance D the greater the risk of misalignmentof the drill. In certain embodiments, the distance D is in the range of5-6 inches.

The mounting portion 46 rotatably supports the targeting arm 34 relativeto the body 32, and ultimately relative to the intramedullary implant 10to which the body is connected. The mounting portion defines a mountingsurface 47 through which the mounting axis 48 passes. The body 32 ispreferably configured so that the mounting surface 47 and axis 48 areparallel to the longitudinal axis L of the member 10 to ensure properand stable alignment when the targeting procedures are conducted.

In one embodiment, the targeting arm 34 includes an elongated bar 60that is mounted for rotation about a pivot axis 53 that falls within theplane defined by the longitudinal axis L and aperture axis A so that thebar rotates in a perpendicular plane. Thus, as shown in FIGS. 1-2, themounting portion 46 includes a pivot post 50 projecting perpendicularlyfrom the mounting surface 47. The post 50 includes a threaded end 51 andterminates in a capture stem 52. The post 50 extends through a pivotbore 61 centrally located in the bar 60. The bar 60 is retained on thepivot post by a knob 56 that includes an internally threaded hub 57 thatengages the threaded end 51 of the post. A capture washer 59 may bepress fit onto the capture stem 52 to capture the knob 56 on the post 50and prevent inadvertent disassembly.

In one embodiment, the pivot post 50 is sized so that the targeting arm34 can freely rotate thereabout and relative to the mounting surface 47.The post 50 is thus sized to permit a gap between the mounting face 63of the bar 60 and the mounting surface 57 of the body 32. A spring 54may be concentrically mounted over the pivot post 50 between the face 63and surface 47 to bias the bar 60 away from the mounting surface. Thisbiased offset thus allows the bar 60 to freely rotate about the post.However, when the bar 60 has been rotated to a desired position, theknob 56 can be manually rotated and threaded down onto the threaded end51 of the pivot post to reduce the offset or gap between mounting face63 and mounting surface 47.

In one embodiment, the knob and spring can be configured so that theknob can be tightened until the face 63 abuts the surface 47. It can beappreciated however, that reliance upon a friction engagement betweenthe targeting arm 34 and the mounting portion 46 of the body 32 may nothold the targeting arm in its proper alignment during use. Thus, inanother aspect, a locking mechanism is provided that removably locks thetargeting arm relative to the mounting portion 46.

In one embodiment the locking mechanism utilizes mutually attractedmagnets mounted on the targeting arm and mounting portion. Thus, asshown in FIGS. 1-2, the bar 60 includes a magnet 69 mounted in a recess70 at a first end 66 of the bar and a magnet 75 mounted in a recess 76at an opposite second end 72. The mounting portion 46 of the body 32includes a locking magnet 78 mounted in a recess 79. The three magnetsare all mounted at the same radius from the pivot axis 53. Thus, whenthe second end 72 is arranged as shown in FIGS. 1-2, the two magnets 75and 78 attract and the magnetic attraction force is sufficiently strongto hold the bar 60 in this position as the targeting apparatus 30 isused in a procedure.

It can be appreciated that when it is desired to rotate the bar 60 sothat the first end 66 and its corresponding magnet 69 are aligned withthe locking magnet 78, the knob 56 is first unthreaded or loosened alongthe pivot post 50. As the knob is loosened the biasing spring 54 pushesthe bar 60 away from the mounting surface 47. When the knob 56 bottomsagainst the capture washer 59 the bar is displaced from the mountingportion 46 that the magnetic attraction between the magnets 75 and 78 issufficiently weak to allow the bar to be easily rotated. Once the barhas been rotated to a position in which the first end 67 is aligned withthe locking magnet, the knob 56 can be re-threaded or tightened onto thepivot post 50 until the spring 54 is fully collapsed. In this position,the magnet 69 in the first end 66 is close enough to the locking magnet78 that the magnetic force can hold or lock the bar 60 in that positionfor use.

It can be appreciated that the interaction of the magnets 69, 75relative to the locking magnet 79 not only effective locks the bar 60 inposition but also assures an accurate alignment of the targeting arm 34in its operative positions. In particular, the lines of magnetic forcebetween the opposing magnets 69/75 and 79 are strongest perpendicular tothe mounting surface 47 and therefore tend to draw the magnets 69/75 inperpendicular alignment with the locking magnet 79. The bar 60 will holdthis aligned position as the knob 56 is tightened.

Maintaining a proper alignment of the bar 60 relative to the mountingportion 46 is important to ensure an accurate alignment of the targetingfeatures of the apparatus 30 relative to the lag screw transverseaperture 14 in the intramedullary implant 10. These targeting featuresinclude a first bore 67 defined at the first end 66 of the bar 60 and asecond bore 73 at the opposite second end 72. Each bore 67, 73 defines acorresponding bore axis 67 a, 73 a that forms a non-perpendicular anglerelative to the face axis 64 of the mounting face 63 of the bar 60. Forinstance, as best seen in FIG. 3 the axis 67 a of the first bore 67 atthe first end of the bar 60 subtends an angle T relative to the mountingaxis 48. In the specific example, this angle T is 125° which correspondsto the indicia 80 inscribed on the first end 66 of the bar. It can bereadily appreciated that the axis 73 a of the second bore 73 in thesecond end of the bar also subtends an angle with the mounting axis 48,which is 130° in the specific example. Thus, in one feature of thisembodiment, the targeting apparatus provides targeting features at twodifferent angles. These two different angles accommodate anintramedullary implant 10 in which the angle X of the aperture axis A iseither 125° or 130°. These two angles are most common in implants ofthis type, but other angles may be accommodated by an appropriatelyoriented one of the bores 67, 73.

The targeting apparatus 30 is thus configured so that when the bar 60 islocked in one of its two positions the targeting features, namely theappropriate one of the bores 67, 73, is aligned with the transverseaperture 14. As shown in FIG. 3, when the second end 72 is locked by thelocking magnet (not shown), the first end is exposed or accessible andthe bore axis 67 a of the first bore 67 is in direct alignment andcollinear with the aperture axis A. Consequently any tool or bonefastener passing through the first bore 67 will be automatically andprecisely aligned with the transverse bore 14 in the intramedullaryimplant 16. In the specific example the first end 66 is in the operableposition. If the aperture 14 in the intramedullary implant 10 is alignedat a 130° angle, the bar 60 of the targeting apparatus 30 can be rotatedso that the second end 72, bearing the indicia 81 identifying the 130°angle, is in the operative position.

As explained above, in some cases a second screw is introduced throughthe intramedullary implant in addition to the lag screw. This secondscrew may be a compression or anti-rotation screw. In those cases, theimplant 10 will include a second transverse aperture 16 with its axisparallel to the aperture axis A of the first aperture 16. In some casesthis second aperture 16 is independent and offset from the firstaperture, while in other cases the two apertures intersect. For implantsof this design, the targeting apparatus 30 may incorporate additionalbores 68 and 74 in the corresponding first and second ends 66 and 72 ofthe targeting arm 34, as best seen in FIGS. 1 and 3. The positioning ofthe added bore 68 relative to the first bore 67, for instance,identically mirrors the positioning of the lag screw bore 14 andcompression/anti-rotation screw bore 14 in the implant 10. Accuratepositioning of the targeting bores 67, 73 will naturally lead toaccurate positioning of the added bores 68, 74.

In the specific embodiment shown in FIGS. 1-3, the most typical lagscrew angles are incorporated into the targeting arm. The targetingfeatures, namely the first and second bores 67, 73, respectively,accurate target the lag screw aperture when the bar 60 is locked to themounting portion 46. When the particular lag screw angle of theintramedullary implant 10 is known, the targeting apparatus 30 can beprepared by rotating the bar 60 so that the appropriate end 66, 72 is inthe operative position. Different bars similar to the bar 60 may also beprovided in which the targeting bores 67, 73 are aligned at angles otherthan the 125° and 130° angles shown in the figures. The bar 60 couldthus be replaced with the alternative bar by removing the knob 57 andthe bar 60 and mounting the alternative bar on the pivot post 50.

One alternative targeting arm 34′ is shown in FIG. 4. This targeting arm34′ includes three bar segments 60 a′, 60 b′ and 60 c′, each defining acorresponding targeting bore 67 a′, 67 b′ and 67 c′. The segments areevenly distributed around and radiate from a central pivot bore 61′ thatis configured to rotatably mount the targeting arm 34′ on the pivot post50 (FIG. 1). Each of the targeting bores 67 a′, 67 b′ and 67 c′ isaligned at a different angle to correspond to one of three lag screwangles for the intramedullary implant 10. With this particularembodiment, the magnetic locking mechanism described above may be usedwith some modification. Specifically, since the bar segments 60 a′, 60b′ and 60 c′ are spaced at 120° intervals, it is not possible to providea magnet 180° a particular bar segment that can engage the lockingmagnet 78 situated in the mounting portion 46. In one modification, themagnet corresponding to each segment may be positioned immediatelyadjacent the pivot bore 61 in alignment with the corresponding segment.The locking magnet 78 would also be relocated to a position adjacent thepivot post 50.

As shown in FIGS. 5-6, an alternative non-magnetic locking mechanism maybe provided to lock the targeting arm in position. In this embodiment, apair of locking pins 85 project from the mounting surface 47″ of themounting portion 46″. The mounting face 63″ of the targeting arm 34″ ismodified form the prior embodiment to include two locking recesses 86.The recesses 86 are positioned to receive the corresponding locking pins85 when the bar 60″ is aligned with the mounting portion 46″, asillustrated in FIG. 6. The interface between the pins 85 and recesses 86is configured to allow rotation of the bar to and from the operablepositions, while positively locking the bar in those operable positions.In one embodiment, the pins are rigidly fixed to the mounting portion sothat the knob must be untightened and the bar 60 elevated sufficientlyabove the mounting surface 47″ to clear the locking pins duringrotation. In another specific embodiment, the locking pins 85 aredepressible so that the pins are depressed as the bar 60″ is rotatedinto one of the two operative positions. The pins may be spring mountedwithin the mounting portion 46″ or may be formed of a resilientlydepressible material.

In an alternative embodiment illustrated in FIGS. 7-9, a targetingapparatus 100 includes a targeting arm 125 that is rotatable in theplane common to the aperture axis A and longitudinal axis L of theintramedullary implant 10. Thu, the targeting apparatus 100 includes agenerally U-shaped body 102 having a mounting end 104 and fastener 106that are configured to mate with features in the proximal end of theimplant, as described above. The intermediate portion 108 of the body102 may define a hand grip feature 109.

In a modification from the apparatus 30 of the prior embodiment, theapparatus 100 includes a mounting portion 112 that is formed by two arms114 that are spaced apart to define a slot 115 therebetween. The armsare configured so that the slot 115 extends parallel to the planedefined by the two implant axes A and L. The arms 115 further definealigned bores 118 for receiving a pivot pin 119, preferably in apress-fit or friction-fit arrangement. The pivot pin 119 defines a pivotaxis 120 about which the targeting arm 125 rotates that is perpendicularto the plane of axes A and L.

The apparatus 100 further includes a targeting arm 125 in the form of abar 126 supported by the pin 119 extending through a pivot bore 127. Thefirst end 130 of the bar 126 defines a first bore 131 along a bore axis131 a, as well as an additional bore 132 where necessary. Likewise, theopposite second end 135 defines a second bore 136 and additional bore137. As with the prior embodiment, the two ends may includecorresponding indicia 138, 139 identifying the particular angularorientations of the targeting bores 131, 136. The arms 114 of themounting portion 112 may further define windows 116 to permit directvisualization of the indicia when the targeting arm is in an operativeposition.

As with the prior embodiment, a locking mechanism may be provided topositively lock the targeting arm in one of its operative positions. Thelocking mechanism may include a locking pin 42 that extends through abore 144 in communication with the slot 115. The end of the locking pin142 is configured to reside within a dimple 146 defined in each end 130,135 of the bar 126. The depth of engagement of the tip of the lockingpin within the dimple 146 is sufficient to restrain or lock thetargeting arm in its operative targeting positions.

The locking pin 142 in one embodiment is retractable from the dimple 146to allow the bar to freely rotate within the slot 115. Thus, a biasingspring 150 may be captured behind the locking pin 142 by a set screw 152threaded engaged within bore 144. The spring 150 thus biases the lockingpin into engagement with the locking dimples in the targeting arm bar126. A manually depressible release button 155 is disposed within across bore 160 in the mounting portion 112 to intersect the locking pinbore 144. The locking pin and release button define complementary matingangled surfaces 156, 158, respectively. The angled surfaces 156, 158 areconfigured and arranged so that when the button 155 is depressed, theinteraction between the angled surfaces tends to push the locking pin142 back against the biasing spring 150 and away from the locking dimple146.

As long as the button is depressed, the mating angled surfaces 156, 158hold the locking pin disengaged from the locking dimple so that the bar126 can freely rotate within the slot 115. When the button 155 isreleased, the biasing spring 150 pushes the locking pin back toward thetargeting arm bar 126 and pushes the button back along the cross bore160. In a specific embodiment, the ends 130, 135 of the bar 126 definearcuate grooves 147 that intersect a corresponding locking dimple 146.These arcuate grooves accept the locking pin while it is extended intothe slot 115 as the bar 126 is rotated and guide the locking pin towardthe deeper locking dimple 146. The biasing spring 150 will then propelthe locking pin into the dimple 146 to hold the bar in the operativetargeting position.

The different positions of the targeting arm 125 are illustrated in thesequence shown in FIGS. 9 a-9 c. In the first position, the second bore136 is oriented with the targeting bore axis 136 a aligned with theaperture axis A at an angle of 130°, as shown in FIG. 9 a. The button155 is depressed to retract the locking mechanism and release thetargeting arm 125 to rotate, as shown in FIG. 9 b. The targeting armcontinues to rotate until the arm is locked in the position shown inFIG. 9 c in which the axis 131 a of the first targeting bore 131 isaligned with the axis A at an angle of 125°.

There are many advantages arising from the various features of each ofthe embodiments of the assembly described herein. It will be noted thatalternative embodiments of the assembly may not include all of thefeatures described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the assembly thatincorporates one or more of the features and fall within the spirit andscope of the present invention as defined by the appended claims.

1. A universal targeting apparatus for targeting a transverse aperturein an intramedullary implant, being one of a rod or bone nail, forintroducing a lag screw into the aperture, in which the transverseaperture has an aperture axis that is oriented at one of at least twoangles relative to a longitudinal axis of the intramedullary implant,comprising: a generally U-shaped body having one end configured to becoupled to the proximal end of the intramedullary implant and a mountingportion at an opposite end of said body, said mounting portion defininga mounting portion longitudinal axis and a plane with the intramedullaryimplant when the body is coupled thereto, said plane containing theaperture axis; and an arm rotatably mounted to said mounting portion ofsaid U-shaped body and having a first portion and a second portionoffset from said first portion, said first portion defining a firstportion longitudinal axis and at least one first bore with alongitudinal first axis, and said second portion defining a secondportion longitudinal axis and at least one second bore with alongitudinal second axis, said arm configured so that said longitudinalfirst axis is aligned with an aperture axis oriented at one of the atleast two angles when said arm is rotated relative to said mountingportion to a first position in which said longitudinal first axisresides within said plane, and so that said longitudinal second axis isaligned with an aperture axis oriented at a different one of the atleast two angles when said arm is rotated to a second position,different than said first position, in which said longitudinal secondaxis resides within said plane, wherein one of said first portion andsaid second portion longitudinal axes is substantially aligned with saidmounting portion longitudinal axis when said arm is in one of said firstposition and said second position and said first portion and secondportion longitudinal axes are misaligned with said mounting portionlongitudinal axis when said arm is not in either of said first positionor said second position, wherein said arm is mounted to said mountingportion to rotate about an axis in said plane.
 2. The universaltargeting apparatus of claim 1, wherein said arm is an elongated bar andsaid first and second portions are at opposite ends thereof.
 3. Theuniversal targeting apparatus of claim 1, wherein said body isconfigured so that said mounting portion is parallel to the longitudinalaxis of the intramedullary implant when the body is coupled thereto. 4.The universal targeting apparatus of claim 3, wherein: said arm is anelongated bar and said first and second portions are at opposite endsthereof; and said arm is mounted on said mounting portion so that saidbar remains parallel to said mounting portion as said arm rotatesrelative thereto.
 5. The universal targeting apparatus of claim 1, inwhich the transverse aperture has an aperture axis that is oriented atone of three different angles relative to the longitudinal axis, theorientation of each of the three different angles defining threedifferent aperture axes, wherein: said arm includes a third portionoffset from said first and second portions, said third portion definingat least one third bore with a longitudinal third axis; and said arm isconfigured so that said longitudinal first axis is aligned with a firstone of the three different aperture axes in said first position, saidlongitudinal second axis is aligned with a second one of the threedifferent aperture axes in said second position, and said longitudinalthird axis is aligned with a third one of the three different apertureaxes when said arm is rotated relative to said mounting portion to athird position in which said longitudinal third axis resides within saidplane.
 6. The universal targeting apparatus of claim 1, furthercomprising a locking mechanism between said body and said arm to locksaid arm in at least one of said first position and said secondposition.
 7. The universal targeting apparatus of claim 6, wherein saidlocking mechanism includes a locking magnet mounted to said mountingportion and each of said first and second portions include acorresponding complementary magnet mounted thereto, each complementarymagnet configured to be magnetically attracted to said locking magnet.8. The universal targeting apparatus of claim 6, wherein said lockingmechanism includes a depressible pin mounted in one of said arm and saidbody, and a recess defined in the other of said arm and said body, saidrecess configured to receive said depressible pin in locking engagement.9. The universal targeting apparatus of claim 8, wherein saiddepressible pin is mounted in said body and each of said first portionand second portion of said arm defines a recess configured to receivesaid depressible pin.
 10. The universal targeting apparatus of claim 8,wherein said depressible pin includes a spring arranged to resistdepressing said pin.
 11. The universal targeting apparatus of claim 10,wherein said locking mechanism includes a manually pressed buttonarranged to depress said pin against said spring.
 12. The universaltargeting apparatus of claim 1, in which the proximal end of theintramedullary implant includes at least two notches offset from eachother, wherein said one end of said body defines at least two prongsconfigured and arranged to engage a corresponding one of the notches.13. The universal targeting apparatus of claim 1, wherein each of saidfirst portion and second portion includes an indicia indicative of thecorresponding one of the aperture axis angles.
 14. The universaltargeting apparatus of claim 1, in which the intramedullary implantincludes an additional transverse aperture for receiving a compressionmember, wherein each of said first and second portions defines anadditional bore aligned with the corresponding first and second bore.